Warsaw: US Secretary of State John Kerry on Tuesday urged European leaders not to allow a row over alleged US spying to disrupt talks with the EU to create the world`s largest free trade zone.

And he renewed calls for US partners to voice their concerns with Washington in order to strengthen "intelligence relationships" in the future.

Speaking on a visit to Poland, Kerry said negotiations with the European Union for a proposed Transatlantic Trade and Investment Partnership (TTIP) would create "one of the most powerful economic forces on the planet and it will raise the standards by which all countries are engaging in economic activities".

The second round of talks are set to resume on November 11 in Brussels after being postponed due to the US government shutdown last month.

But they have also been clouded by a wave of outrage among European leaders -- most notably the leader of Europe`s economic powerhouse German Chancellor Angela Merkel -- after the revelations US security services had tapped European leaders` phones.

"We need to understand as partners we`re all in this together. We`re all in the effort to try to provide protection to our citizens," Kerry said at a joint press conference with his Polish counterpart Radoslaw Sikorski.

The United States was working to "strike the right balance between protecting our citizens and obviously the privacy of all of our citizens", he added.

US President Barack Obama has ordered a review of the intelligence services in the light ot the revelations from former US National Security Agency employee Edward Snowden.

Kerry arrived yesterday in Warsaw for a brief visit during which he will also discuss defence and the proposed deployment of a US missile defence system in Poland by 2018.

Sikorski said earlier this year that Poland would spend 33.6 billion euros (USD 43.3 billion) to upgrade the army and "build up its deterrence forces".

Kerry was also due to visit Lask air base to address US and Polish pilots who have been doing joint training since November 2012.

The top US diplomat, who last week said that the spying activities had gone too far, urged European leaders to voice their concerns.

"We want to hear from our allies, we want to have this conversation," Kerry said.

"If we get this right, which we will, we can not only alleviate concerns but we can actually strengthen our intelligence relationships going forward."

But he urged the Europeans not to confuse the issue with the trade talks.